On-farm production of liquefied catfish protein

Abstract

A method and the equipment used to process channel catfish ( Ictalurus punctatus) offal into a liquid catfish protein (LCP) suitable for use as an animal feedstuff component is described. This process uses the offal following cleaning of the catfish for commercial use, i.e., without additional grinding or chopping. Small amounts of either hydrochloric acid or formic acid can be used to liquefy the catfish offal in 2 h or less. The liquefaction is conducted in a drum fitted with a baffle. The drum is heated to 50°C with water from an overhead manifold while turning on a drum roller. Bones and unliquefied material are removed by screening to yield LCP at pH 4.5. Variations in the processing conditions — grinding, agitation rate, acid employed, and time — did not alter significantly the amount of crude protein or the essential amino acid profile. Acid selection altered the amount of essential free amino acids found, with hydrochloric acid producing the lesser amount. Reducing the agitation rate lowered the amount of essential free amino acids. Comparison of the essential amino acid profile of the LCP with those of catfish, menhaden and herring meals showed lower amounts of these acids but sufficient to warrant use as a feed component.